The present invention relates to apparatus for conditioning tobacco, and more particularly to improvements in apparatus for controlled reduction of moisture content of tobacco particles in the form of whole leaves, ribs, stem, laminae and/or shreds.
It is already known to condition moist tobacco particles in a zone which is defined by a heated conveyor and wherein a current of heated gaseous fluid is caused to flow counter to the direction of tobacco transport. For example, the conveyor may include a rotary drum which surrounds the conditioning zone and is heated by one or more steam-circulating coils which rotate therewith to agitate the particles of tobacco in the conditioning zone. The gaseous fluid is normally air which is conveyed by a fan or the like and is heated before it enters the downstream end of the conditioning zone.
It is further known to recirculate a portion of moisture-laden fluid which issues from the downstream end of the conditioning zone and to mix such intercepted portion of moisture-laden fluid with a fresh fluid. As a rule, the percentage of moisture-laden fluid which is recirculated through the conditioning zone is rather low, i.e., the major part of such fluid is allowed to escape into the atmosphere. This is undesirable for several reasons, e.g., because the moisture-laden fluid has a pungent odor and also because substantial amounts of heat are dissipated into the atmosphere.